#include<iostream>
using namespace std;
typedef long long LL;
const int N = 1e5 + 10;
int n;
int arr[N];
int temp[N];
LL merge_sort(int l, int r)
{
	if (l >= r) {
		return 0;
	}
	int mid = (l + r) >> 1;
	LL res = merge_sort(l, mid) + merge_sort(mid + 1, r);
	int i = l;
	int j = mid + 1;
	int k = 0;
	while (i <= mid && j <= r) {
		if (arr[i] < arr[j]) {
			temp[k++] = arr[i++];
		}
		else {
			temp[k++] = arr[j++];
			res += mid - i + 1;
		}
	}
	while (i <= mid) {
		temp[k++] = arr[i++];
	}
	while (j <= r) {
		temp[k++] = arr[j++];
	}
	for (int i = l, j = 0; i <= r; i++, j++) {
		arr[i] = temp[j];
	}
	return res;
}
int main()
{
	cin >> n;
	for (int i = 0; i < n; i++) {
		cin >> arr[i];
	}
	LL res = merge_sort(0, n - 1);
	cout << res << endl;
	return 0;
}